key: cord-0874952-4wz534sc
authors: Garnier, Marc; Julian, Nathan; Velly, Lionel
title: Heat moisture exchange/high-efficiency particulate filters and the risk of contamination of the ventilatory circuit and patient environment with SARS-CoV-2: A brief report
date: 2022-04-26
journal: Anaesth Crit Care Pain Med
DOI: 10.1016/j.accpm.2022.101065
sha: 231d5415b4482b51620579f525b3388f68555976
doc_id: 874952
cord_uid: 4wz534sc

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Marc GARNIER 1 , Nathan JULIAN 2,3 , Lionel VELLY 4, 5 Dear Editor, During the COVID-19 pandemic, the efficiency of the filtering devices used in ventilated patients returned to the forefront, notably because the protection from crosscontamination of the intensive care unit (ICU) staff quickly appeared as an important challenge. In the ICU, it is recommended to use a filter between the patient and the ventilator [1] , providing both microbiological filtration and heating and humidification of the inspired gases (Heat and Moisture Exchange -HME -function). The high efficiency of filtration (going up to the High-Efficiency Particulate Air -HEPA -qualification) [2] is certified by manufacturers following bench tests. To our knowledge, few studies were conducted in clinical settings, particularly considering the COVID-19 context. Thus, the precautionary principle took precedence and some ventilator manufacturers [3] or learned societies [4] suggested the use of a second HEPA filter at the expiratory port of the ventilator for enhanced safety.

We performed an observational multicentre study with the aim of testing the potential contamination of the ventilatory circuit with SARS-CoV-2. We included all the patients hospitalised in the 3 participating ICU for severe COVID-19 confirmed by RT-PCR on a lower respiratory tract sample, requiring invasive mechanical ventilation between the 27 th of April 2020 and the 07 th of May 2020, and in whom the attending physician prescribed a bronchial aspirate to document a suspicion of ventilator-associated pneumonia. Then, contamination of the respiratory circuit with SARS-CoV-2 was assessed thanks to three swabs performed: 1) in the closed suctioning system (CSS) that was placed between the intubation tube and the HME/HEPA filter just after its change for a clean device before sampling the bronchial aspirate; 2) at the Y-piece between the HME/HEPA filter and the Our observations reinforce bench test results regarding the filtration performance of HME/HEPA filters, allowing a second filter at the expiratory port of the respirator to be dispensed with a fairly high level of safety.

J o u r n a l P r e -p r o o f

This work has been approved by the French Society of Anaesthesia and Intensive Care Medicine (SFAR) ethical committee (CERAR -IRB00010254 #2020-109). According to French law and due to the non-interventional design of the study, patient's consent was waived by the ethical committee. Thus, oral and written information was given to patients who survive their critical COVID-19, who could then decline inclusion in the study.

Not applicable

Data are available from the corresponding author on reasonable request.

All the authors declare that they do not have any competing interest with the current work.

This work has not been funded by any external source. 

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